People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

Stress

In psychology, stress is a concept about condition that can be described as: feeling of strain and pressure, feeling of anxiety and being overwhelmed, overall irritability, feeling of insecure, nervousness, social withdrawal, loss of appetite, depression, panic attacks, exhaustion, high or low blood pressure, skin problems, insomnia, lack of sexual desire (sexual dysfunction), migraine, gastrointestinal problems.